JPH11245008A - Continuous casting method of steel and equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to use a mold which does not easily cause vertical corner cracks in a cast piece, at less processing and maintenance costs, by casting the cast piece using the mold without round corner and chamfering the four corners or upper two corners of the cast piece through roll reduction or burner scarf before straightening. SOLUTION: Since a mold 1 without round corners is used, the mold processing and maintenance costs are low and vertical corner crack of the cast piece does not occur. Since a chamfering equipment 2 consisting of a roll 4 or a burner 5 is provided between the mold 1 and a straightening machine 3 formed with pinch rolls and the four corners or upper two corners of the cast piece are chamfered by means of roll reduction or burner scarf before straightening, the occurrence of horizontal corner crack when straightening and fall flaw when rolling can be prevented. If the four corners of the cast piece are chamfered, it is effective for preventing both horizontal corner crack and fall flaw.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for continuous casting of steel, and more particularly to a method and an apparatus for continuous casting of steel which are suitable when the slab is a bloom or a billet.

[0002]

2. Description of the Related Art In continuous casting of blooms and billets, lateral cracks which are likely to occur at the time of straightening of a slab and corner falling flaws (falling flaws) which are likely to occur at the time of forming or piercing rolling in the next step. Figure 1 to prevent
As shown in (c), there is known a casting method in which a corner R of 3 mm or more is provided in a mold 1a so that a corner of a slab is rounded.

[0003]

According to the above-mentioned conventional casting method in which a corner R is provided in a mold, it is possible to prevent or reduce falling flaws and lateral cracks in the corner, but the processing cost and maintenance cost of the mold are high. Further, as shown in FIG. 2, there is a problem that corner vertical cracks are easily generated in the slab. The present invention solves this problem, and can use a mold with low processing cost and low maintenance cost, which does not easily cause vertical cracks in the cast slab, and which can effectively prevent lateral cracks and falling flaws in corners. It is an object to provide a casting method and equipment.

[0004]

According to the present invention, in a continuous casting method of steel, a slab is cast using a mold having a corner R of 0, and four corners or two corners on the upper surface of the slab are corrected before straightening. A continuous casting method for steel, characterized in that chamfering is performed by roll reduction or burner scarf. Further, the present invention provides a steel continuous casting facility, a mold having a corner R of 0, a straightening machine for straightening a slab cast with the mold, and a square or upper surface of the slab between the mold and the straightening machine. And a chamfering device comprising a roll or a burner for chamfering the two corners.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, as shown in FIG. 1 (b), since a mold 1 having no corner R is used, the processing cost and maintenance cost of the mold can be reduced. Also, the occurrence of vertical cracks in the corner of the slab is eliminated. FIG.
As shown in (a), (d) and (e), a surface composed of a roll (chamfer roll) 4 or a burner (chamfer burner) 5 between the mold 1 and a straightening machine 3 composed of a pinch roll. Picking device 2
Before the straightening, the four corners of the slab or the two corners on the upper surface were chamfered by roll reduction or burner scarf, so that the occurrence of corner lateral cracks at the time of straightening and falling flaws at the time of rolling were effectively prevented. Can be prevented.

FIGS. 1 (d) and 1 (e) show examples of chamfering four corners of a slab, which is particularly effective for both corner lateral cracks and falling flaws. . On the other hand, for example, in the case where another countermeasure against falling flaws is taken on the rolling process side and importance is placed on prevention of lateral corner cracking in the continuous casting process, the stress state at the time of straightening becomes the tensile side. Only the upper two corners may be chamfered.

[0007]

EXAMPLE The present invention was carried out by the continuous casting equipment shown in FIG. 1 (a), and the tendency of occurrence of lateral cracks and falling flaws was compared with a conventional casting method using a mold having a corner R. FIGS. 3A and 3B are graphs showing the influence of the corner R and the amount of corner chamfering on the tendency of occurrence of corner lateral cracking, and FIG. 3C is an explanatory diagram of the definition of the amount of corner chamfering. In addition,
The corner chamfering was performed by rolling down two corners of the upper surface. As is clear from comparison of FIGS. 3A and 3B,
Before straightening using a mold without corner R, the chamfer amount of the corner is about 4mm
If chamfering is performed as described above, the same effect of preventing corner lateral cracking as when a mold having a corner radius of about 12 mm or more is used is obtained.

FIGS. 4 (a) and 4 (b) are graphs showing the influence of the corner R and the amount of corner chamfering on the tendency of the generation of a falling flaw. The corner chamfering here was performed with a burner scarf on the four corners. As is clear from comparison between FIGS. 4 (a) and 4 (b), if a mold without a corner R was used and chamfering was performed with a corner chamfer of about 5 mm or more before straightening, a mold with a corner R of about 4 mm or more was used. It has the same effect of preventing falling flaws as in the case.

[0009]

As described above, according to the present invention, in continuous casting of blooms and billets, it is possible to use a mold that is low in processing cost and maintenance cost and that does not easily cause vertical cracks in the slab. Has an excellent effect that can be effectively prevented.

[Brief description of the drawings]

FIG. 1A is an overall view of a continuous casting facility showing one embodiment of the present invention, FIG. 1B is a cross-sectional view of a mold having a corner R = 0,
(C) is a sectional view of a mold having a corner R> 0, (d) is a conceptual diagram of a roll-type chamfering device, and (e) is a conceptual diagram of a burner-type chamfering device.

FIG. 2 is a graph showing a relationship between a corner vertical crack length and a corner R.

3 (a) and 3 (b) are graphs showing the influence of a corner R and a corner chamfering amount on the tendency of occurrence of a corner lateral crack, and FIG. 3 (c) is an explanatory diagram of the definition of the corner chamfering amount.

FIGS. 4A and 4B are graphs showing the influence of the corner R and the amount of corner chamfering on the tendency of occurrence of falling flaws.

[Description of Signs] 1 Mold (Corner R = 0) 1a Mold (Corner R> 0) 2 Chamfering Device 3 Straightener (Pinch Roll) 4 Roll (Chamfer Roll) 5 Burner (Chamfer Burner)

Claims (2)

[Claims] In a continuous casting method for steel, a slab is cast using a mold having a corner R of 0, and the slab is cast before straightening.
A continuous casting method for steel, comprising chamfering a corner or two corners on the upper surface side with a roll under pressure or a burner scarf. 2. In a steel continuous casting facility, a mold having a corner R of 0, a straightening machine for straightening a slab cast with the mold, and a square or upper surface of the slab between the mold and the straightening machine. A continuous casting facility for steel, comprising: a chamfering device comprising a roll or a burner for chamfering two corners.